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The gradient of the line L1 is -4/5.It cuts the y axis at the same point as the line...

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inquire123 | Student | (Level 3) eNoter

Posted April 20, 2013 at 4:05 AM via web

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The gradient of the line L1 is -4/5.It cuts the y axis at the same point as the line L2:7x+4y-12.Find the equation of L1

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justaguide | College Teacher | (Level 2) Distinguished Educator

Posted April 20, 2013 at 4:27 AM (Answer #1)

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The equation of line L2 is 7x+4y-12 = 0.

Rewriting this in the slope intercept form `y = 12/4 - 7/4x` . The y-intercept of the line is (0, 3).

As the line L1 has the same y-intercept as L2 but the slope of the line is -4/5, its equation is: `y = (-4/5)x + 3`

=> 5y = -4x + 15

=> 4x + 5y - 15 = 0

The equation of L1 is 4x + 5y - 15 = 0

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